In a nutshell: the djvu file is a very advanced format for storing scanned books efficiently. Accordingly many books scanned by google, which are stored on www.archive.org are saved in the djvu file as well. Normally you won't have a white background in those old books (unless it was digitally removed). Now djvu has the option just to display the foreground and just ignore the background. And in the source text it is a single line as I reported in the bug report. I went through the effort in writing to the Guys in Kiev and pointed them to that particular line.. nothing happened.

So tonight, I went through the trouble and recompiled the old djvu file viewer from pocketbook-free (which ment, that I had to first recompile all the corresponding djvulibre libraries, which kept me occupied for quite a while). Finally, I changed the line to not render the page as "color" but display either only the foreground or just display the text mask.

The results are stunning. What a contrast you can get out of that ebook!

In a while I will upload some screenshots. Then you can make your own judgement. At the moment, I've just added the new compiled viewer just to the context menu so that I have the choice to either open it with low contrast in "colour mode" (the default mode. It might be useful if you have primarily picutres in your djvu file and not text) or in the high contrast mode, which is obviously a pleasure to the eye when reading text.

And in the end we want to be reading text with our ebook reader, don't we?

Is there some interest in the contrast enhanced djviewer app? Shall I upload it as well?

On the left side is how a typical djvu file from a scanned book will look on the latest Pocketbook firmware (2.0.4, January 2011).

On the right you will see the result of my adapted version of the djviewer which displays only the foreground mask and this in black/white leading to the highest readability and best contrast.

The first file shows that it is not just a black and white filter but true layer selection: it only displays the text layer and not the dark colour of the book cover.

The last picture shows clearly how bad the contrast is if the pages are rendered with the "colour" mode on a 8bit grayscale ebook... and the screenshot is looking even better than it does in reality! In reality the text is barely readable. However, if you compare it with the modified version you will see the significant improvement.

Those are one and the same file. Just displayed with the native pocketbook viewer (left) and with my viewer (right).

On the left side is how a typical djvu file from a scanned book will look on the latest Pocketbook firmware (2.0.4, January 2011).

On the right you will see the result of my adapted version of the djviewer which displays only the foreground mask and this in black/white leading to the highest readability and best contrast.

The first file shows that it is not just a black and white filter but true layer selection: it only displays the text layer and not the dark colour of the book cover.

The last picture shows clearly how bad the contrast is if the pages are rendered with the "colour" mode on a 8bit grayscale ebook... and the screenshot is looking even better than it does in reality! In reality the text is barely readable. However, if you compare it with the modified version you will see the significant improvement.

Those are one and the same file. Just displayed with the native pocketbook viewer (left) and with my viewer (right).

1) unzip the attached file djviewer-bw.zip
2) copy djviewer-bw.app into the folder system/bin on the internal memory
3) place the test file called textbook.djvu somewhere
4) edit extensions.cfg in system/config and add the bold part:

Code:

djvu:@DJVU_file:1:djviewer-bw.app,djviewer.app:ICON_DJVU

5) Enjoy reading with an excellent contrast.

These steps will make my version of the djvu viewer the default viewer. If you want to open the file with the viewer provided with the pocketbook just select djview from the context menu of the file. The file will open in exactly the same place and with the same zoom and orientation as the file in my version of the viewer.

Also, I've attached the screenshots of the attached djvu file. The left is with pocketbooks viewer and the right with my version.

wow!!
review, you're restless..
you should get paid by pocketbook for all this hard work, thank you so much.
karma on its way.
t
P.S. sorry for being OT, but I would like to profit on your djvu knowledge:
recently I converted a 2000 pages color scanned pdf that pb did not show correctly into djvu format.
now pb shows and handles it correctly, but from a 200MB file I got a 500 MB djvu (???). wasn't it a compression format? I used default settings (pdf2djvu GUI on win7), except that I checked no metadata and no hyperlinks. just a couriosity..

@Review: I know you guys are computers gurus, but I have a question from a non-savy computer: These steps are done when you connect the PB to the computer or need to be done using poterm(like hacking the PB)?

I dont see when I connect the PB to computer, I can see the system file but is empty..

thanks!

Quote:

Originally Posted by review

1) unzip the attached file djviewer-bw.zip
2) copy djviewer-bw.app into the folder system/bin on the internal memory
3) place the test file called textbook.djvu somewhere
4) edit extensions.cfg in system/config and add the bold part:

Code:

djvu:@DJVU_file:1:djviewer-bw.app,djviewer.app:ICON_DJVU

5) Enjoy reading with an excellent contrast.

These steps will make my version of the djvu viewer the default viewer. If you want to open the file with the viewer provided with the pocketbook just select djview from the context menu of the file. The file will open in exactly the same place and with the same zoom and orientation as the file in my version of the viewer.

Also, I've attached the screenshots of the attached djvu file. The left is with pocketbooks viewer and the right with my version.

1) if on the internal memory there is only system but no config in system just create an empty folder called config.
2) open notepad and copy, paste the line mentioned above and save it as extensions.cfg on the system/config folder

This is not a hack! No poterm or other funny stuff. This is a completly independent application for your pocketbook. Keep me updated how you're getting on and don't hesitate if something still does not make sense.

1) if on the internal memory there is only system but no config in system just create an empty folder called config.
2) open notepad and copy, paste the line mentioned above and save it as extensions.cfg on the system/config folder

This is not a hack! No poterm or other funny stuff. This is a completly independent application for your pocketbook. Keep me updated how you're getting on and don't hesitate if something still does not make sense.